1
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Nithianantham S, Iwanski MK, Gaska I, Pandey H, Bodrug T, Inagaki S, Major J, Brouhard GJ, Gheber L, Rosenfeld SS, Forth S, Hendricks AG, Al-Bassam J. The kinesin-5 tail and bipolar minifilament domains are the origin of its microtubule crosslinking and sliding activity. Mol Biol Cell 2023; 34:ar111. [PMID: 37610838 PMCID: PMC10559304 DOI: 10.1091/mbc.e23-07-0287] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2023] [Revised: 08/07/2023] [Accepted: 08/15/2023] [Indexed: 08/25/2023] Open
Abstract
Kinesin-5 crosslinks and slides apart microtubules to assemble, elongate, and maintain the mitotic spindle. Kinesin-5 is a tetramer, where two N-terminal motor domains are positioned at each end of the motor, and the coiled-coil stalk domains are organized into a tetrameric bundle through the bipolar assembly (BASS) domain. To dissect the function of the individual structural elements of the motor, we constructed a minimal kinesin-5 tetramer (mini-tetramer). We determined the x-ray structure of the extended, 34-nm BASS domain. Guided by these structural studies, we generated active bipolar kinesin-5 mini-tetramer motors from Drosophila melanogastor and human orthologues which are half the length of native kinesin-5. We then used these kinesin-5 mini-tetramers to examine the role of two unique structural adaptations of kinesin-5: 1) the length and flexibility of the tetramer, and 2) the C-terminal tails which interact with the motor domains to coordinate their ATPase activity. The C-terminal domain causes frequent pausing and clustering of kinesin-5. By comparing microtubule crosslinking and sliding by mini-tetramer and full-length kinesin-5, we find that both the length and flexibility of kinesin-5 and the C-terminal tails govern its ability to crosslink microtubules. Once crosslinked, stiffer mini-tetramers slide antiparallel microtubules more efficiently than full-length motors.
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Affiliation(s)
- Stanley Nithianantham
- Department of Molecular and Cellular Biology, University of California, Davis, CA 95616
| | - Malina K. Iwanski
- Departments of Biology and Bioengineering, McGill University, Montreal, Quebec Canada H3A 1B1
| | - Ignas Gaska
- Department of Biological Sciences, Rensselaer Polytechnic Institute, Troy, NY 12180
| | - Himanshu Pandey
- Department of Molecular and Cellular Biology, University of California, Davis, CA 95616
| | - Tatyana Bodrug
- Department of Molecular and Cellular Biology, University of California, Davis, CA 95616
| | - Sayaka Inagaki
- Department of Pharmacology, Mayo Clinic, Jacksonville, FL 32224
| | - Jennifer Major
- Department of Pharmacology, Mayo Clinic, Jacksonville, FL 32224
| | - Gary J. Brouhard
- Departments of Biology and Bioengineering, McGill University, Montreal, Quebec Canada H3A 1B1
| | - Larissa Gheber
- Department of Chemistry, The Ben Gurion University, Ber Sheva, Israel
| | | | - Scott Forth
- Department of Biological Sciences, Rensselaer Polytechnic Institute, Troy, NY 12180
| | - Adam G. Hendricks
- Departments of Biology and Bioengineering, McGill University, Montreal, Quebec Canada H3A 1B1
| | - Jawdat Al-Bassam
- Department of Molecular and Cellular Biology, University of California, Davis, CA 95616
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2
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Sherwin D, Gutierrez-Morton E, Bokros M, Haluska C, Wang Y. A new layer of regulation of chromosomal passenger complex (CPC) translocation in budding yeast. Mol Biol Cell 2023; 34:ar97. [PMID: 37405742 PMCID: PMC10551702 DOI: 10.1091/mbc.e23-02-0063] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2023] [Revised: 06/27/2023] [Accepted: 06/28/2023] [Indexed: 07/06/2023] Open
Abstract
The conserved chromosomal passenger complex (CPC) consists of Ipl1Aurora-B, Sli15INCENP, Bir1Survivin, and Nbl1Borealin, and localizes at the kinetochore/centromere to correct kinetochore attachment errors and to prevent checkpoint silencing. After anaphase entry, the CPC moves from the kinetochore/centromere to the spindle. In budding yeast, CPC subunit Sli15 is phosphorylated by both cyclin-dependent kinase (CDK) and Ipl1 kinase. Following anaphase onset, activated Cdc14 phosphatase reverses Sli15 phosphorylation imposed by CDK to promote CPC translocation. Although abolished Sli15 phosphorylation imposed by Ipl1 also causes CPC translocation, the regulation of Ipl1-imposed Sli15 phosphorylation remains unclear. In addition to Sli15, Cdc14 also dephosphorylates Fin1, a regulatory subunit of protein phosphatase 1 (PP1), to enable kinetochore localization of Fin1-PP1. Here, we present evidence supporting the notion that kinetochore-localized Fin1-PP1 likely reverses Ipl1-imposed Sli15 phosphorylation to promote CPC translocation from the kinetochore/centromere to the spindle. Importantly, premature Fin1 kinetochore localization or phospho-deficient sli15 mutation causes checkpoint defects in response to tensionless attachments, resulting in chromosome missegregation. In addition, our data indicate that reversion of CDK- and Ipl1-imposed Sli15 phosphorylation shows an additive effect on CPC translocation. Together, these results reveal a previously unidentified pathway to regulate CPC translocation, which is important for accurate chromosome segregation.
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Affiliation(s)
- Delaney Sherwin
- Department of Biomedical Sciences, College of Medicine, Florida State University, Tallahassee, FL 32306-4300
| | - Emily Gutierrez-Morton
- Department of Biomedical Sciences, College of Medicine, Florida State University, Tallahassee, FL 32306-4300
| | - Michael Bokros
- Department of Biomedical Sciences, College of Medicine, Florida State University, Tallahassee, FL 32306-4300
| | - Cory Haluska
- Department of Biomedical Sciences, College of Medicine, Florida State University, Tallahassee, FL 32306-4300
| | - Yanchang Wang
- Department of Biomedical Sciences, College of Medicine, Florida State University, Tallahassee, FL 32306-4300
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3
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She ZY, Zhong N, Wei YL. Kinesin-5 Eg5 mediates centrosome separation to control spindle assembly in spermatocytes. Chromosoma 2022; 131:87-105. [PMID: 35437661 DOI: 10.1007/s00412-022-00772-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Revised: 03/12/2022] [Accepted: 04/08/2022] [Indexed: 11/25/2022]
Abstract
Timely and accurate centrosome separation is critical for bipolar spindle organization and faithful chromosome segregation during cell division. Kinesin-5 Eg5 is essential for centrosome separation and spindle organization in somatic cells; however, the detailed functions and mechanisms of Eg5 in spermatocytes remain unclear. In this study, we show that Eg5 proteins are located at spindle microtubules and centrosomes in spermatocytes both in vivo and in vitro. We reveal that the spermatocytes are arrested at metaphase I in seminiferous tubules after Eg5 inhibition. Eg5 ablation results in cell cycle arrest, the formation of monopolar spindle, and chromosome misalignment in cultured GC-2 spd cells. Importantly, we find that the long-term inhibition of Eg5 results in an increased number of centrosomes and chromosomal instability in spermatocytes. Our findings indicate that Eg5 mediates centrosome separation to control spindle assembly and chromosome alignment in spermatocytes, which finally contribute to chromosome stability and faithful cell division of the spermatocytes.
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Affiliation(s)
- Zhen-Yu She
- Department of Cell Biology and Genetics, The School of Basic Medical Sciences, Fujian Medical University, Fuzhou, 350122, Fujian, China.
- Key Laboratory of Stem Cell Engineering and Regenerative Medicine, Fujian Province University, Fuzhou, 350122, Fujian, China.
| | - Ning Zhong
- Department of Cell Biology and Genetics, The School of Basic Medical Sciences, Fujian Medical University, Fuzhou, 350122, Fujian, China
- Key Laboratory of Stem Cell Engineering and Regenerative Medicine, Fujian Province University, Fuzhou, 350122, Fujian, China
| | - Ya-Lan Wei
- Fujian Obstetrics and Gynecology Hospital, Fuzhou, 350011, Fujian, China
- Medical Research Center, Fujian Maternity and Child Health Hospital, Affiliated Hospital of Fujian Medical University, Fuzhou, 350001, Fujian, China
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4
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Orr B, De Sousa F, Gomes AM, Afonso O, Ferreira LT, Figueiredo AC, Maiato H. An anaphase surveillance mechanism prevents micronuclei formation from frequent chromosome segregation errors. Cell Rep 2021; 37:109783. [PMID: 34758324 PMCID: PMC8595644 DOI: 10.1016/j.celrep.2021.109783] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Revised: 07/15/2021] [Accepted: 08/26/2021] [Indexed: 12/25/2022] Open
Abstract
Micronuclei are a hallmark of cancer and several other human disorders. Recently, micronuclei were implicated in chromothripsis, a series of massive genomic rearrangements that may drive tumor evolution and progression. Here, we show that Aurora B kinase mediates a surveillance mechanism that integrates error correction during anaphase with spatial control of nuclear envelope reassembly to prevent micronuclei formation. Using high-resolution live-cell imaging of human cancer and non-cancer cells, we uncover that anaphase lagging chromosomes are more frequent than previously anticipated, yet they rarely form micronuclei. Micronuclei formation from anaphase lagging chromosomes is prevented by a midzone-based Aurora B phosphorylation gradient that stabilizes kinetochore-microtubule attachments and assists spindle forces required for anaphase error correction while delaying nuclear envelope reassembly on lagging chromosomes, independently of microtubule density. We propose that a midzone-based Aurora B phosphorylation gradient actively monitors and corrects frequent chromosome segregation errors to prevent micronuclei formation during human cell division. Anaphase lagging chromosomes are frequent but rarely form micronuclei A midzone Aurora B activity gradient prevents micronuclei from segregation errors Midzone Aurora B assists spindle forces at the kinetochores to correct errors Aurora B spatially regulates nuclear envelope reformation on lagging chromosomes
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Affiliation(s)
- Bernardo Orr
- Chromosome Instability & Dynamics Group, i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Rua Alfredo Allen 208, 4200-135 Porto, Portugal; Instituto de Biologia Molecular e Celular, Universidade do Porto, Rua Alfredo Allen 208, 4200-135 Porto, Portugal
| | - Filipe De Sousa
- Chromosome Instability & Dynamics Group, i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Rua Alfredo Allen 208, 4200-135 Porto, Portugal; Instituto de Biologia Molecular e Celular, Universidade do Porto, Rua Alfredo Allen 208, 4200-135 Porto, Portugal
| | - Ana Margarida Gomes
- Chromosome Instability & Dynamics Group, i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Rua Alfredo Allen 208, 4200-135 Porto, Portugal; Instituto de Biologia Molecular e Celular, Universidade do Porto, Rua Alfredo Allen 208, 4200-135 Porto, Portugal
| | - Olga Afonso
- Chromosome Instability & Dynamics Group, i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Rua Alfredo Allen 208, 4200-135 Porto, Portugal; Instituto de Biologia Molecular e Celular, Universidade do Porto, Rua Alfredo Allen 208, 4200-135 Porto, Portugal
| | - Luísa T Ferreira
- Chromosome Instability & Dynamics Group, i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Rua Alfredo Allen 208, 4200-135 Porto, Portugal; Instituto de Biologia Molecular e Celular, Universidade do Porto, Rua Alfredo Allen 208, 4200-135 Porto, Portugal
| | - Ana C Figueiredo
- Chromosome Instability & Dynamics Group, i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Rua Alfredo Allen 208, 4200-135 Porto, Portugal; Instituto de Biologia Molecular e Celular, Universidade do Porto, Rua Alfredo Allen 208, 4200-135 Porto, Portugal
| | - Helder Maiato
- Chromosome Instability & Dynamics Group, i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Rua Alfredo Allen 208, 4200-135 Porto, Portugal; Instituto de Biologia Molecular e Celular, Universidade do Porto, Rua Alfredo Allen 208, 4200-135 Porto, Portugal; Cell Division Group, Department of Biomedicine, Faculdade de Medicina, Universidade do Porto, Alameda Prof. Hernâni Monteiro, 4200-319 Porto, Portugal.
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5
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Pandey H, Popov M, Goldstein-Levitin A, Gheber L. Mechanisms by Which Kinesin-5 Motors Perform Their Multiple Intracellular Functions. Int J Mol Sci 2021; 22:6420. [PMID: 34203964 PMCID: PMC8232732 DOI: 10.3390/ijms22126420] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Accepted: 06/07/2021] [Indexed: 11/16/2022] Open
Abstract
Bipolar kinesin-5 motor proteins perform multiple intracellular functions, mainly during mitotic cell division. Their specialized structural characteristics enable these motors to perform their essential functions by crosslinking and sliding apart antiparallel microtubules (MTs). In this review, we discuss the specialized structural features of kinesin-5 motors, and the mechanisms by which these features relate to kinesin-5 functions and motile properties. In addition, we discuss the multiple roles of the kinesin-5 motors in dividing as well as in non-dividing cells, and examine their roles in pathogenetic conditions. We describe the recently discovered bidirectional motility in fungi kinesin-5 motors, and discuss its possible physiological relevance. Finally, we also focus on the multiple mechanisms of regulation of these unique motor proteins.
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Affiliation(s)
| | | | | | - Larisa Gheber
- Department of Chemistry and Ilse Katz Institute for Nanoscale Science and Technology, Ben-Gurion University of the Negev, P.O. Box 653, Beer-Sheva 84105, Israel; (H.P.); (M.P.); (A.G.-L.)
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6
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Finardi A, Massari LF, Visintin R. Anaphase Bridges: Not All Natural Fibers Are Healthy. Genes (Basel) 2020; 11:genes11080902. [PMID: 32784550 PMCID: PMC7464157 DOI: 10.3390/genes11080902] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Revised: 08/04/2020] [Accepted: 08/05/2020] [Indexed: 02/07/2023] Open
Abstract
At each round of cell division, the DNA must be correctly duplicated and distributed between the two daughter cells to maintain genome identity. In order to achieve proper chromosome replication and segregation, sister chromatids must be recognized as such and kept together until their separation. This process of cohesion is mainly achieved through proteinaceous linkages of cohesin complexes, which are loaded on the sister chromatids as they are generated during S phase. Cohesion between sister chromatids must be fully removed at anaphase to allow chromosome segregation. Other (non-proteinaceous) sources of cohesion between sister chromatids consist of DNA linkages or sister chromatid intertwines. DNA linkages are a natural consequence of DNA replication, but must be timely resolved before chromosome segregation to avoid the arising of DNA lesions and genome instability, a hallmark of cancer development. As complete resolution of sister chromatid intertwines only occurs during chromosome segregation, it is not clear whether DNA linkages that persist in mitosis are simply an unwanted leftover or whether they have a functional role. In this review, we provide an overview of DNA linkages between sister chromatids, from their origin to their resolution, and we discuss the consequences of a failure in their detection and processing and speculate on their potential role.
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Affiliation(s)
- Alice Finardi
- Department of Experimental Oncology, IEO, European Institute of Oncology IRCCS, 20139 Milan, Italy;
| | - Lucia F. Massari
- The Wellcome Centre for Cell Biology, Institute of Cell Biology, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3BF, UK;
| | - Rosella Visintin
- Department of Experimental Oncology, IEO, European Institute of Oncology IRCCS, 20139 Milan, Italy;
- Correspondence: ; Tel.: +39-02-5748-9859; Fax: +39-02-9437-5991
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7
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She ZY, Zhong N, Yu KW, Xiao Y, Wei YL, Lin Y, Li YL, Lu MH. Kinesin-5 Eg5 is essential for spindle assembly and chromosome alignment of mouse spermatocytes. Cell Div 2020; 15:6. [PMID: 32165913 PMCID: PMC7060529 DOI: 10.1186/s13008-020-00063-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Accepted: 02/29/2020] [Indexed: 11/10/2022] Open
Abstract
Background Microtubule organization is essential for bipolar spindle assembly and chromosome segregation, which contribute to genome stability. Kinesin-5 Eg5 is known to be a crucial regulator in centrosome separation and spindle assembly in mammalian somatic cells, however, the functions and mechanisms of Eg5 in male meiotic cell division remain largely unknown. Results In this study, we have found that Eg5 proteins are expressed in mouse spermatogonia, spermatocytes and spermatids. After Eg5 inhibition by specific inhibitors Monastrol, STLC and Dimethylenastron, the meiotic spindles of dividing spermatocytes show spindle collapse and the defects in bipolar spindle formation. We demonstrate that Eg5 regulates spindle bipolarity and the maintenance of meiotic spindles in meiosis. Eg5 inhibition leads to monopolar spindles, spindle abnormalities and chromosome misalignment in cultured GC-2 spd cells. Furthermore, Eg5 inhibition results in the decrease of the spermatids and the abnormalities in mature sperms. Conclusions Our results have revealed an important role of kinesin-5 Eg5 in male meiosis and the maintenance of male fertility. We demonstrate that Eg5 is crucial for bipolar spindle assembly and chromosome alignment in dividing spermatocytes. Our data provide insights into the functions of Eg5 in meiotic spindle assembly of dividing spermatocytes.
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Affiliation(s)
- Zhen-Yu She
- 1Department of Cell Biology and Genetics, The School of Basic Medical Sciences, Fujian Medical University, Fuzhou, 350122 Fujian China.,Key Laboratory of Stem Cell Engineering and Regenerative Medicine, Fujian Province University, Fuzhou, 350122 Fujian China
| | - Ning Zhong
- 1Department of Cell Biology and Genetics, The School of Basic Medical Sciences, Fujian Medical University, Fuzhou, 350122 Fujian China
| | - Kai-Wei Yu
- 1Department of Cell Biology and Genetics, The School of Basic Medical Sciences, Fujian Medical University, Fuzhou, 350122 Fujian China
| | - Yu Xiao
- 1Department of Cell Biology and Genetics, The School of Basic Medical Sciences, Fujian Medical University, Fuzhou, 350122 Fujian China
| | - Ya-Lan Wei
- Fujian Obstetrics and Gynecology Hospital, Fuzhou, 350001 Fujian China.,4Fujian Provincial Children's Hospital, Fujian Provincial Maternity and Children's Hospital, Affiliated Hospital of Fujian Medical University, Fuzhou, 350001 Fujian China
| | - Yang Lin
- 1Department of Cell Biology and Genetics, The School of Basic Medical Sciences, Fujian Medical University, Fuzhou, 350122 Fujian China
| | - Yue-Ling Li
- 1Department of Cell Biology and Genetics, The School of Basic Medical Sciences, Fujian Medical University, Fuzhou, 350122 Fujian China
| | - Ming-Hui Lu
- 1Department of Cell Biology and Genetics, The School of Basic Medical Sciences, Fujian Medical University, Fuzhou, 350122 Fujian China
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8
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Mann BJ, Wadsworth P. Kinesin-5 Regulation and Function in Mitosis. Trends Cell Biol 2019; 29:66-79. [DOI: 10.1016/j.tcb.2018.08.004] [Citation(s) in RCA: 74] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2018] [Revised: 07/30/2018] [Accepted: 08/17/2018] [Indexed: 11/16/2022]
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9
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Sherin L, Farwa S, Sohail A, Li Z, Bég OA. Cancer drug therapy and stochastic modeling of "nano-motors". Int J Nanomedicine 2018; 13:6429-6440. [PMID: 30410329 PMCID: PMC6198871 DOI: 10.2147/ijn.s168780] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Background Controlled inhibition of kinesin motor proteins is highly desired in the field of oncology. Among other interventions, there exists “targeted chemotherapeutic regime/options” of selective Eg5 competitive and allosteric inhibitors, inducing cancer cell apoptosis and tumor regression with improved safety profiles. Research question Though promising, such studies are still under clinical trials, for the discovery of efficient and least harmful Eg5 inhibitors. The aim of this research was to bridge the computational modeling approach with drug design and therapy of cancer cells. Methods A computational model, interfaced with the clinical data of “Eg5 dynamics” and “inhibitors” via special functions, is presented in this article. Comparisons are made for the drug efficacy, and the threshold values are predicted through numerical simulations. Results Results are obtained to depict the dynamics induced by ispinesib, when used as an inhibitor of kinesin Eg5, on cancer cell lines.
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Affiliation(s)
- Lubna Sherin
- Department of Chemistry, COMSATS University Islamabad, Lahore 54000, Pakistan
| | - Shabieh Farwa
- Department of Mathematics, COMSATS University Islamabad, Wah Cantt, Pakistan
| | - Ayesha Sohail
- Department of Mathematics, COMSATS University Islamabad, Lahore 54000, Pakistan,
| | - Zhiwu Li
- Institute of Systems Engineering, Macau University of Science and Technology, Taipa, Macau.,School of Electro-Mechanical Engineering, Xidian University, Xi'an 710071, China
| | - O Anwar Bég
- Fluid Mechanics, Spray Research Group, Mechanical and Petroleum Engineering, School of Computing, Science and Engineering, G77, University of Salford, Manchester M54WT, UK
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10
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Goldstein A, Siegler N, Goldman D, Judah H, Valk E, Kõivomägi M, Loog M, Gheber L. Three Cdk1 sites in the kinesin-5 Cin8 catalytic domain coordinate motor localization and activity during anaphase. Cell Mol Life Sci 2017; 74:3395-3412. [PMID: 28455557 PMCID: PMC11107736 DOI: 10.1007/s00018-017-2523-z] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2016] [Revised: 04/06/2017] [Accepted: 04/10/2017] [Indexed: 12/22/2022]
Abstract
The bipolar kinesin-5 motors perform essential functions in mitotic spindle dynamics. We previously demonstrated that phosphorylation of at least one of the Cdk1 sites in the catalytic domain of the Saccharomyces cerevisiae kinesin-5 Cin8 (S277, T285, S493) regulates its localization to the anaphase spindle. The contribution of these three sites to phospho-regulation of Cin8, as well as the timing of such contributions, remains unknown. Here, we examined the function and spindle localization of phospho-deficient (serine/threonine to alanine) and phospho-mimic (serine/threonine to aspartic acid) Cin8 mutants. In vitro, the three Cdk1 sites undergo phosphorylation by Clb2-Cdk1. In cells, phosphorylation of Cin8 affects two aspects of its localization to the anaphase spindle, translocation from the spindle-pole bodies (SPBs) region to spindle microtubules (MTs) and the midzone, and detachment from the mitotic spindle. We found that phosphorylation of S277 is essential for the translocation of Cin8 from SPBs to spindle MTs and the subsequent detachment from the spindle. Phosphorylation of T285 mainly affects the detachment of Cin8 from spindle MTs during anaphase, while phosphorylation at S493 affects both the translocation of Cin8 from SPBs to the spindle and detachment from the spindle. Only S493 phosphorylation affected the anaphase spindle elongation rate. We conclude that each phosphorylation site plays a unique role in regulating Cin8 functions and postulate a model in which the timing and extent of phosphorylation of the three sites orchestrates the anaphase function of Cin8.
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Affiliation(s)
- Alina Goldstein
- Department of Chemistry and Ilse Katz Institute for Nanoscale Science and Technology, Ben-Gurion University of the Negev, PO Box 653, 84105, Beer-Sheva, Israel
| | - Nurit Siegler
- Department of Chemistry and Ilse Katz Institute for Nanoscale Science and Technology, Ben-Gurion University of the Negev, PO Box 653, 84105, Beer-Sheva, Israel
| | - Darya Goldman
- Department of Chemistry and Ilse Katz Institute for Nanoscale Science and Technology, Ben-Gurion University of the Negev, PO Box 653, 84105, Beer-Sheva, Israel
| | - Haim Judah
- Department of Chemistry and Ilse Katz Institute for Nanoscale Science and Technology, Ben-Gurion University of the Negev, PO Box 653, 84105, Beer-Sheva, Israel
| | - Ervin Valk
- Institute of Technology, University of Tartu, Tartu, Estonia
| | - Mardo Kõivomägi
- Institute of Technology, University of Tartu, Tartu, Estonia
| | - Mart Loog
- Institute of Technology, University of Tartu, Tartu, Estonia
| | - Larisa Gheber
- Department of Chemistry and Ilse Katz Institute for Nanoscale Science and Technology, Ben-Gurion University of the Negev, PO Box 653, 84105, Beer-Sheva, Israel.
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11
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Scholey JM, Civelekoglu-Scholey G, Brust-Mascher I. Anaphase B. BIOLOGY 2016; 5:biology5040051. [PMID: 27941648 PMCID: PMC5192431 DOI: 10.3390/biology5040051] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/28/2016] [Revised: 11/30/2016] [Accepted: 12/01/2016] [Indexed: 11/16/2022]
Abstract
Anaphase B spindle elongation is characterized by the sliding apart of overlapping antiparallel interpolar (ip) microtubules (MTs) as the two opposite spindle poles separate, pulling along disjoined sister chromatids, thereby contributing to chromosome segregation and the propagation of all cellular life. The major biochemical “modules” that cooperate to mediate pole–pole separation include: (i) midzone pushing or (ii) braking by MT crosslinkers, such as kinesin-5 motors, which facilitate or restrict the outward sliding of antiparallel interpolar MTs (ipMTs); (iii) cortical pulling by disassembling astral MTs (aMTs) and/or dynein motors that pull aMTs outwards; (iv) ipMT plus end dynamics, notably net polymerization; and (v) ipMT minus end depolymerization manifest as poleward flux. The differential combination of these modules in different cell types produces diversity in the anaphase B mechanism. Combinations of antagonist modules can create a force balance that maintains the dynamic pre-anaphase B spindle at constant length. Tipping such a force balance at anaphase B onset can initiate and control the rate of spindle elongation. The activities of the basic motor filament components of the anaphase B machinery are controlled by a network of non-motor MT-associated proteins (MAPs), for example the key MT cross-linker, Ase1p/PRC1, and various cell-cycle kinases, phosphatases, and proteases. This review focuses on the molecular mechanisms of anaphase B spindle elongation in eukaryotic cells and briefly mentions bacterial DNA segregation systems that operate by spindle elongation.
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Affiliation(s)
- Jonathan M Scholey
- Department of Molecular and Cell Biology, University of California, Davis, CA 95616, USA.
| | | | - Ingrid Brust-Mascher
- Department of Anatomy, Physiology and Cell Biology, School of Veterinary Medicine, University of California, Davis, CA 95616, USA.
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12
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Sturgill EG, Norris SR, Guo Y, Ohi R. Kinesin-5 inhibitor resistance is driven by kinesin-12. J Cell Biol 2016; 213:213-27. [PMID: 27091450 PMCID: PMC5084272 DOI: 10.1083/jcb.201507036] [Citation(s) in RCA: 74] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2015] [Accepted: 03/10/2016] [Indexed: 12/27/2022] Open
Abstract
The kinesin-5 Eg5 is essential for mitotic progression, and the lethal effects of Eg5 inhibitors make these inhibitors attractive candidates for chemotherapy drugs. Sturgill et al. show that kinesin-12 and a nonmotile Eg5 mutant form an alternative spindle assembly pathway that provides resistance to Eg5 inhibitors. The microtubule (MT) cytoskeleton bipolarizes at the onset of mitosis to form the spindle. In animal cells, the kinesin-5 Eg5 primarily drives this reorganization by actively sliding MTs apart. Its primacy during spindle assembly renders Eg5 essential for mitotic progression, demonstrated by the lethal effects of kinesin-5/Eg5 inhibitors (K5Is) administered in cell culture. However, cultured cells can acquire resistance to K5Is, indicative of alternative spindle assembly mechanisms and/or pharmacological failure. Through characterization of novel K5I-resistant cell lines, we unveil an Eg5 motility-independent spindle assembly pathway that involves both an Eg5 rigor mutant and the kinesin-12 Kif15. This pathway centers on spindle MT bundling instead of Kif15 overexpression, distinguishing it from those previously described. We further show that large populations (∼107 cells) of HeLa cells require Kif15 to survive K5I treatment. Overall, this study provides insight into the functional plasticity of mitotic kinesins during spindle assembly and has important implications for the development of antimitotic regimens that target this process.
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Affiliation(s)
- Emma G Sturgill
- Department of Cell and Developmental Biology, Vanderbilt University Medical Center, Nashville, TN 37232
| | - Stephen R Norris
- Department of Cell and Developmental Biology, Vanderbilt University Medical Center, Nashville, TN 37232
| | - Yan Guo
- Department of Cancer Biology, Vanderbilt University Medical Center, Nashville, TN 37232
| | - Ryoma Ohi
- Department of Cell and Developmental Biology, Vanderbilt University Medical Center, Nashville, TN 37232
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13
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Weiderhold KN, Fadri-Moskwik M, Pan J, Nishino M, Chuang C, Deeraksa A, Lin SH, Yu-Lee LY. Dynamic Phosphorylation of NudC by Aurora B in Cytokinesis. PLoS One 2016; 11:e0153455. [PMID: 27074040 PMCID: PMC4830538 DOI: 10.1371/journal.pone.0153455] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2015] [Accepted: 03/30/2016] [Indexed: 01/06/2023] Open
Abstract
Nuclear distribution protein C (NudC) is a mitotic regulator that plays a role in cytokinesis. However, how NudC is regulated during cytokinesis remains unclear. Here, we show that NudC is phosphorylated by Aurora B, a kinase critical for cell abscission. NudC is co-localized with Aurora B at the midbody and co-immunoprecipitated with Aurora B in mitosis. Inhibition of Aurora B by ZM447439 reduced NudC phosphorylation, suggesting that NudC is an Aurora B substrate in vivo. We identified T40 on NudC as an Aurora B phosphorylation site. NudC depletion resulted in cytokinesis failure with a dramatic elongation of the intercellular bridge between daughter cells, sustained Aurora B activity at the midbody, and reduced cell abscission. These cytokinetic defects can be rescued by the ectopic expression of wild-type NudC. Reconstitution with T40A phospho-defective NudC was found to rescue the cytokinesis defect. In contrast, reconstitution with the T40D phospho-mimetic NudC was inefficient in supporting the completion of cytokinesis. These results suggest that that dynamic phosphorylation of NudC by Aurora B regulates cytokinesis.
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Affiliation(s)
- Kimberly N. Weiderhold
- Program in Integrative Molecular and Biomedical Sciences, Baylor College of Medicine, Houston, Texas, United States of America
| | - Maria Fadri-Moskwik
- Department of Medicine, Section of Allergy Immunology and Rheumatology, Baylor College of Medicine, Houston, Texas, United States of America
| | - Jing Pan
- Department of Medicine, Section of Allergy Immunology and Rheumatology, Baylor College of Medicine, Houston, Texas, United States of America
| | - Michiya Nishino
- Program in Integrative Molecular and Biomedical Sciences, Baylor College of Medicine, Houston, Texas, United States of America
| | - Carol Chuang
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas, United States of America
| | - Arpaporn Deeraksa
- Department of Medicine, Section of Allergy Immunology and Rheumatology, Baylor College of Medicine, Houston, Texas, United States of America
| | - Sue-Hwa Lin
- Department of Translational Molecular Pathology, The University of Texas M.D. Anderson Cancer Center, Houston, Texas, United States of America
| | - Li-Yuan Yu-Lee
- Program in Integrative Molecular and Biomedical Sciences, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Medicine, Section of Allergy Immunology and Rheumatology, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas, United States of America
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14
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Shimamoto Y, Forth S, Kapoor TM. Measuring Pushing and Braking Forces Generated by Ensembles of Kinesin-5 Crosslinking Two Microtubules. Dev Cell 2016; 34:669-81. [PMID: 26418296 DOI: 10.1016/j.devcel.2015.08.017] [Citation(s) in RCA: 101] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2015] [Revised: 07/07/2015] [Accepted: 08/26/2015] [Indexed: 01/10/2023]
Abstract
The proper organization of the microtubule-based mitotic spindle is proposed to depend on nanometer-sized motor proteins generating forces that scale with a micron-sized geometric feature, such as microtubule overlap length. However, it is unclear whether such regulation can be achieved by any mitotic motor protein. Here, we employ an optical-trap- and total internal reflection fluorescence (TIRF)-based assay to show that ensembles of kinesin-5, a conserved mitotic motor protein, can push apart overlapping antiparallel microtubules to generate a force whose magnitude scales with filament overlap length. We also find that kinesin-5 can produce overlap-length-dependent "brake-like" resistance against relative microtubule sliding in both parallel and antiparallel geometries, an activity that has been suggested by cell biological studies but had not been directly measured. Together, these findings, along with numerical simulations, reveal how a motor protein can function as an analog converter, "reading" simple geometric and dynamic features in cytoskeletal networks to produce regulated force outputs.
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Affiliation(s)
- Yuta Shimamoto
- Laboratory of Chemistry and Cell Biology, The Rockefeller University, New York, NY 10065, USA; JST PRESTO, The Rockefeller University, New York, NY 10065, USA
| | - Scott Forth
- Laboratory of Chemistry and Cell Biology, The Rockefeller University, New York, NY 10065, USA
| | - Tarun M Kapoor
- Laboratory of Chemistry and Cell Biology, The Rockefeller University, New York, NY 10065, USA.
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15
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Fraschini R. Factors that Control Mitotic Spindle Dynamics. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 925:89-101. [PMID: 27722958 DOI: 10.1007/5584_2016_74] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Mitosis is the last phase of the cell cycle and it leads to the formation of two daughter cells with the same genetic information. This process must occurr in a very precise way and this task is essential to preserve genetic stability and to maintain cell viability. Accurate chromosome segregation during mitosis is brought about by an important cellular organelle: the mitotic spindle. This structure is made of microtubules, polymers of alpha and beta tubulin, and it is highly dynamic during the cell cycle: it emanates from two microtubules organizing centers (Spindle Pole Bodies, SPBs, in yeast) that are essential to build a short bipolar spindle, and it undergoes two steps of elongation during anaphase A and anaphase B in order to separate sister chromatids. Several proteins are involved in the control of mitotic spindle dynamics and their activity is tightly coordinated with other cell cycle events and with cell cycle progression.
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Affiliation(s)
- Roberta Fraschini
- Dipartimento di Biotecnologie e Bioscienze, Università degli Studi di Milano-Bicocca, Piazza della Scienza 2, 20126, Milan, Italy.
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16
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Qian H, Xu X, Niklason LE. Bmk-1 regulates lifespan in Caenorhabditis elegans by activating hsp-16. Oncotarget 2015; 6:18790-9. [PMID: 26299918 PMCID: PMC4662456 DOI: 10.18632/oncotarget.4618] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2015] [Accepted: 07/20/2015] [Indexed: 12/23/2022] Open
Abstract
The genetics of aging is typically concerned with lifespan determination that is associated with alterations in expression levels or mutations of particular genes. Previous reports in C. elegans have shown that the bmk-1 gene has important functions in chromosome segregation, and this has been confirmed with its mammalian homolog, KIF11. However, this gene has never been implicated in aging or lifespan regulation. Here we show that the bmk-1 gene is an important lifespan regulator in worms. We show that reducing bmk-1 expression using RNAi shortens worm lifespan by 32%, while over-expression of bmk-1 extends worm lifespan by 25%, and enhances heat-shock stress resistance. Moreover, bmk-1 over-expression increases the level of hsp-16 and decreases ced-3 in C. elegans. Genetic epistasis analysis reveals that hsp-16 is essential for the lifespan extension by bmk-1. These findings suggest that bmk-1 may act through enhanced hsp-16 function to protect cells from stress and inhibit the apoptosis pathway, thereby conferring worm longevity. Though it remains unclear whether this is a distinct function from chromosomal segregation, bmk-1 is a potential new target for extension of lifespan and enhancement of healthspan.
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Affiliation(s)
- Hong Qian
- Department of Anesthesiology, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Xiangru Xu
- Department of Anesthesiology, Yale University School of Medicine, New Haven, CT 06520, USA.,Max Planck Institute for Biology of Ageing, 50931, Cologne, Germany
| | - Laura E Niklason
- Department of Anesthesiology, Yale University School of Medicine, New Haven, CT 06520, USA
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17
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Candida albicans Kinesin Kar3 Depends on a Cik1-Like Regulatory Partner Protein for Its Roles in Mating, Cell Morphogenesis, and Bipolar Spindle Formation. EUKARYOTIC CELL 2015; 14:755-74. [PMID: 26024903 DOI: 10.1128/ec.00015-15] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2015] [Accepted: 05/26/2015] [Indexed: 02/05/2023]
Abstract
Candida albicans is a major fungal pathogen whose virulence is associated with its ability to transition from a budding yeast form to invasive hyphal filaments. The kinesin-14 family member CaKar3 is required for transition between these morphological states, as well as for mitotic progression and karyogamy. While kinesin-14 proteins are ubiquitous, CaKar3 homologs in hemiascomycete fungi are unique because they form heterodimers with noncatalytic kinesin-like proteins. Thus, CaKar3-based motors may represent a novel antifungal drug target. We have identified and examined the roles of a kinesin-like regulator of CaKar3. We show that orf19.306 (dubbed CaCIK1) encodes a protein that forms a heterodimer with CaKar3, localizes CaKar3 to spindle pole bodies, and can bind microtubules and influence CaKar3 mechanochemistry despite lacking an ATPase activity of its own. Similar to CaKar3 depletion, loss of CaCik1 results in cell cycle arrest, filamentation defects, and an inability to undergo karyogamy. Furthermore, an examination of the spindle structure in cells lacking either of these proteins shows that a large proportion have a monopolar spindle or two dissociated half-spindles, a phenotype unique to the C. albicans kinesin-14 homolog. These findings provide new insights into mitotic spindle structure and kinesin motor function in C. albicans and identify a potentially vulnerable target for antifungal drug development.
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18
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Roccuzzo M, Visintin C, Tili F, Visintin R. FEAR-mediated activation of Cdc14 is the limiting step for spindle elongation and anaphase progression. Nat Cell Biol 2015; 17:251-61. [PMID: 25706236 DOI: 10.1038/ncb3105] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2014] [Accepted: 01/09/2015] [Indexed: 01/01/2023]
Abstract
Cleavage of cohesins and cyclin-dependent kinase (CDK) inhibition are thought to be sufficient for triggering chromosome segregation. Here we identify an essential requirement for anaphase chromosome movement. We show that, at anaphase onset, the phosphatase Cdc14 and the polo-like kinase Cdc5 are redundantly required to drive spindle elongation. This role of Cdc14 is mediated by the FEAR network, a group of proteins that activates Cdc14 at anaphase onset, and we suggest that Cdc5 facilitates both Cdc14 activation and CDK inhibition. We further identify the kinesin-5 motor protein Cin8 as a key target of Cdc14. Indeed, Cin8 mutants lacking critical CDK phosphorylation sites suppress the requirement for Cdc14 and Cdc5 in anaphase spindle elongation. Our results indicate that cohesin dissolution and CDK inhibition per se are not sufficient to drive sister chromatid segregation but that the motor protein Cin8 must be activated to elongate the spindle.
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Affiliation(s)
- Michela Roccuzzo
- Department of Experimental Oncology, European Institute of Oncology, Milan 20139, Italy
| | - Clara Visintin
- Department of Experimental Oncology, European Institute of Oncology, Milan 20139, Italy
| | - Federico Tili
- Department of Experimental Oncology, European Institute of Oncology, Milan 20139, Italy
| | - Rosella Visintin
- Department of Experimental Oncology, European Institute of Oncology, Milan 20139, Italy
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19
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Affiliation(s)
- Helder Maiato
- Chromosome Instability & Dynamics Laboratory; Instituto de Biologia Molecular e Celular, Universidade do Porto; Porto Portugal
- Cell Division Unit, Department of Experimental Biology; Faculdade de Medicina, Universidade do Porto; Porto Portugal
| | - Olga Afonso
- Chromosome Instability & Dynamics Laboratory; Instituto de Biologia Molecular e Celular, Universidade do Porto; Porto Portugal
- Cell Division Unit, Department of Experimental Biology; Faculdade de Medicina, Universidade do Porto; Porto Portugal
| | - Irina Matos
- Chromosome Instability & Dynamics Laboratory; Instituto de Biologia Molecular e Celular, Universidade do Porto; Porto Portugal
- Cell Division Unit, Department of Experimental Biology; Faculdade de Medicina, Universidade do Porto; Porto Portugal
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20
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Rizk RS, Discipio KA, Proudfoot KG, Gupta ML. The kinesin-8 Kip3 scales anaphase spindle length by suppression of midzone microtubule polymerization. ACTA ACUST UNITED AC 2014; 204:965-75. [PMID: 24616221 PMCID: PMC3998799 DOI: 10.1083/jcb.201312039] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Mitotic spindle function is critical for cell division and genomic stability. During anaphase, the elongating spindle physically segregates the sister chromatids. However, the molecular mechanisms that determine the extent of anaphase spindle elongation remain largely unclear. In a screen of yeast mutants with altered spindle length, we identified the kinesin-8 Kip3 as essential to scale spindle length with cell size. Kip3 is a multifunctional motor protein with microtubule depolymerase, plus-end motility, and antiparallel sliding activities. Here we demonstrate that the depolymerase activity is indispensable to control spindle length, whereas the motility and sliding activities are not sufficient. Furthermore, the microtubule-destabilizing activity is required to counteract Stu2/XMAP215-mediated microtubule polymerization so that spindle elongation terminates once spindles reach the appropriate final length. Our data support a model where Kip3 directly suppresses spindle microtubule polymerization, limiting midzone length. As a result, sliding forces within the midzone cannot buckle spindle microtubules, which allows the cell boundary to define the extent of spindle elongation.
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Affiliation(s)
- Rania S Rizk
- Department of Molecular Genetics and Cell Biology, The University of Chicago, Chicago, IL 60637
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21
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Marston AL. Chromosome segregation in budding yeast: sister chromatid cohesion and related mechanisms. Genetics 2014; 196:31-63. [PMID: 24395824 PMCID: PMC3872193 DOI: 10.1534/genetics.112.145144] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2013] [Accepted: 09/18/2013] [Indexed: 12/28/2022] Open
Abstract
Studies on budding yeast have exposed the highly conserved mechanisms by which duplicated chromosomes are evenly distributed to daughter cells at the metaphase-anaphase transition. The establishment of proteinaceous bridges between sister chromatids, a function provided by a ring-shaped complex known as cohesin, is central to accurate segregation. It is the destruction of this cohesin that triggers the segregation of chromosomes following their proper attachment to microtubules. Since it is irreversible, this process must be tightly controlled and driven to completion. Furthermore, during meiosis, modifications must be put in place to allow the segregation of maternal and paternal chromosomes in the first division for gamete formation. Here, I review the pioneering work from budding yeast that has led to a molecular understanding of the establishment and destruction of cohesion.
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Affiliation(s)
- Adele L Marston
- The Wellcome Trust Centre for Cell Biology, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3JR, United Kingdom
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22
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Collins E, Mann BJ, Wadsworth P. Eg5 restricts anaphase B spindle elongation in mammalian cells. Cytoskeleton (Hoboken) 2013; 71:136-44. [PMID: 24285623 DOI: 10.1002/cm.21158] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2013] [Revised: 10/29/2013] [Accepted: 11/11/2013] [Indexed: 01/31/2023]
Abstract
During anaphase, overlapping antiparallel microtubules in the spindle interzone elongate and contribute to chromosome segregation. Kinesin-5 family members are required for spindle elongation in some cells, but in other cases they restrict elongation acting like a brake. To determine how kinesin-5 contributes to spindle elongation in mammalian cells, we treated LLC-Pk1 epithelial cells with small molecule inhibitors of the mammalian kinesin-5, Eg5, at anaphase onset and measured the rate and extent of spindle pole separation using multidimensional tracking of centrosomes in cells expressing GFP-γ-tubulin. Centrosome separation was biphasic, with an initial fast phase followed by a slower phase. Treatment with the small molecule inhibitor, STLC, which weakens the interaction of Eg5 with microtubules, resulted in an increase in the rate of centrosome separation. Conversely, treatment with FCPT, which induces a rigor-like interaction of Eg5 with microtubules, reduced the rate of spindle elongation. In control cells, GFP-Eg5 was localized to spindle microtubules and accumulated in the interzone as anaphase progressed. Spindle fluorescence of GFP-Eg5 was decreased following treatment with STLC and increased in cells treated with FCPT. In anaphase cells, cortical dynein increases and rocking motion of spindle poles was detected consistent with the possibility that dynein mediates spindle elongation. In summary, our results demonstrate that Eg5 is not required for spindle elongation, and in fact, restricts the rate of spindle elongation in mammalian cells.
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Affiliation(s)
- Elizabeth Collins
- Department of Biology University of Massachusetts Amherst, Amherst, Massachusetts
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23
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Fridman V, Gerson-Gurwitz A, Shapira O, Movshovich N, Lakämper S, Schmidt CF, Gheber L. Kinesin-5 Kip1 is a bi-directional motor that stabilizes microtubules and tracks their plus-ends in vivo. J Cell Sci 2013; 126:4147-59. [PMID: 23868978 DOI: 10.1242/jcs.125153] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
In this study, we examined the anaphase functions of the S. cerevisiae kinesin-5 homolog Kip1. We show that Kip1 is attached to the mitotic spindle midzone during late anaphase. This attachment is essential to stabilize interpolar microtubule (iMTs) plus-ends. By detailed examination of iMT dynamics we show that at the end of anaphase, iMTs depolymerize in two stages: during the first stage, one pair of anti-parallel iMTs depolymerizes at a velocity of 7.7 µm/minute; during the second stage, ∼90 seconds later, the remaining pair of iMTs depolymerizes at a slower velocity of 5.4 µm/minute. We show that upon the second depolymerization stage, which coincides with spindle breakdown, Kip1 follows the plus-ends of depolymerizing iMTs and translocates toward the spindle poles. This movement is independent of mitotic microtubule motor proteins or the major plus-end binding or tracking proteins. In addition, we show that Kip1 processively tracks the plus-ends of growing and shrinking MTs, both inside and outside the nucleus. The plus-end tracking activity of Kip1 requires its catalytic motor function, because a rigor mutant of Kip1 does not exhibit this activity. Finally, we show that Kip1 is a bi-directional motor: in vitro, at high ionic strength conditions, single Kip1 molecules move processively in the minus-end direction of the MTs, whereas in a multi-motor gliding assay, Kip1 is plus-end directed. The bi-directionality and plus-end tracking activity of Kip1, properties revealed here for the first time, allow Kip1 to perform its multiple functions in mitotic spindle dynamics and to partition the 2-micron plasmid.
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Affiliation(s)
- Vladimir Fridman
- Department of Chemistry, Ben-Gurion University of the Negev, Beer-Sheva, Israel
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24
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Tension sensing by Aurora B kinase is independent of survivin-based centromere localization. Nature 2013; 497:118-21. [PMID: 23604256 PMCID: PMC3644022 DOI: 10.1038/nature12057] [Citation(s) in RCA: 107] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2012] [Accepted: 03/05/2013] [Indexed: 12/18/2022]
Abstract
Accurate segregation of the replicated genome requires chromosome biorientation on the spindle. Biorientation is ensured by Aurora B kinase, a member of the 4-subunit chromosomal passenger complex (CPC)1,2. Localization of the CPC to the inner centromere is central to the current model for how tension ensures chromosome biorientation—kinetochore-spindle attachments not under tension remain close to the inner centromere and are destabilized by Aurora B phosphorylation, whereas kinetochores under tension are pulled away from the influence of Aurora B, stabilizing their microtubule attachments3–5. Here we show that an engineered truncation of the INCENP/Sli15 subunit of budding yeast CPC that eliminates association with the inner centromere nevertheless supports proper chromosome segregation during both mitosis and meiosis. Truncated INCENP/Sli15 suppresses the deletion phenotypes of the inner centromere-targeting proteins Survivin/Bir1, Borealin/Nbl1, Bub1 and Sgo16. Unlike wildtype INCENP/Sli15, truncated INCENP/Sli15 localizes to pre-anaphase spindle microtubules. Premature targeting of full-length INCENP/Sli15 to microtubules by preventing Cdk1 phosphorylation also suppresses inviability of Survivin/Bir1 deletion. These results suggest that activation of Aurora B/Ipl1 by clustering either on chromatin or on microtubules is sufficient for chromosome biorientation.
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25
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Goulet A, Moores C. New insights into the mechanism of force generation by kinesin-5 molecular motors. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2013; 304:419-66. [PMID: 23809441 DOI: 10.1016/b978-0-12-407696-9.00008-7] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Kinesin-5 motors are members of a superfamily of microtubule-dependent ATPases and are widely conserved among eukaryotes. Kinesin-5s typically form homotetramers with pairs of motor domains located at either end of a dumbbell-shaped molecule. This quaternary structure enables cross-linking and ATP-driven sliding of pairs of microtubules, although the exact molecular mechanism of this activity is still unclear. Kinesin-5 function has been characterized in greatest detail in cell division, although a number of interphase roles have also been defined. The kinesin-5 ATPase is tuned for slow microtubule sliding rather than cellular transport and-in vertebrates-can be inhibited specifically by allosteric small molecules currently in cancer clinical trials. The biophysical and structural basis of kinesin-5 mechanochemistry is being elucidated and has provided further insight into kinesin-5 activities. However, it is likely that the precise mechanism of these important motors has evolved according to functional context and regulation in individual organisms.
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Affiliation(s)
- Adeline Goulet
- Institute of Structural and Molecular Biology, Birkbeck College, London, United Kingdom
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26
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Kaplan KB, Li R. A prescription for 'stress'--the role of Hsp90 in genome stability and cellular adaptation. Trends Cell Biol 2012; 22:576-83. [PMID: 22959309 DOI: 10.1016/j.tcb.2012.08.006] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2012] [Revised: 08/08/2012] [Accepted: 08/12/2012] [Indexed: 12/11/2022]
Abstract
Changes in cell homeostasis, or cell 'stress', are thought to tax the ability of the Hsp90 chaperone to facilitate an array of processes critical for genome maintenance. Here, we review the current understanding of how the Hsp90 chaperone machinery ensures the function of proteins important for DNA repair, recombination, and chromosome segregation. We discuss the idea that cell stress can overload Hsp90, resulting in genomic instability that may have important implications for stress adaptation and selection. The importance of Hsp90 in genome maintenance and its limited capacity to buffer the proteome may underlie the initiation or progression of diseases such as cancer.
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Affiliation(s)
- Kenneth B Kaplan
- Department of Molecular and Cellular Biology, University of California, Davis, CA 95616, USA.
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27
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Ma N, Titus J, Gable A, Ross JL, Wadsworth P. TPX2 regulates the localization and activity of Eg5 in the mammalian mitotic spindle. ACTA ACUST UNITED AC 2011; 195:87-98. [PMID: 21969468 PMCID: PMC3187703 DOI: 10.1083/jcb.201106149] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
TPX2 promotes mitotic spindle formation by enhancing Eg5 accumulation on microtubules and limiting motor activity. Mitotic spindle assembly requires the regulated activity of numerous spindle-associated proteins. In mammalian cells, the Kinesin-5 motor Eg5 interacts with the spindle assembly factor TPX2, but how this interaction contributes to spindle formation and function is not established. Using bacterial artificial chromosome technology, we generated cells expressing TPX2 lacking the Eg5 interaction domain. Spindles in these cells were highly disorganized with multiple spindle poles. The TPX2–Eg5 interaction was required for kinetochore fiber formation and contributed to Eg5 localization to spindle microtubules but not spindle poles. Microinjection of the Eg5-binding domain of TPX2 resulted in spindle elongation, indicating that the interaction of Eg5 with TPX2 reduces motor activity. Consistent with this possibility, we found that TPX2 reduced the velocity of Eg5-dependent microtubule gliding, inhibited microtubule sliding, and resulted in the accumulation of motor on microtubules. These results establish a novel function of TPX2 in regulating the location and activity of the mitotic motor Eg5.
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Affiliation(s)
- Nan Ma
- Department of Biology, University of Massachusetts, Amherst, MA 01003, USA
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28
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Short B. Passengers operate the brakes. J Biophys Biochem Cytol 2011. [PMCID: PMC3080265 DOI: 10.1083/jcb.1932iti1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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